Stabilization of a Shallow Roadway Embankment Failure Using Turf Reinforcement Mats and Driven Anchors-PPT Presentation

PPT Presentation

Pdf Summary

Hurricane Helene’s intense rainfall in September 2024 triggered shallow failures along the roadway embankment at 224 West Wade Hampton Boulevard. Three soil borings found 13–18 feet of very loose to loose silty sand fill over residual soil and partially weathered rock; no groundwater was observed during drilling. The distress was interpreted as shallow instability within the fill.<br /><br />To restore stability with limited cost, excavation, and site disturbance, the project team selected an anchored turf reinforcement mat (TRM) system over soil nails or a gravity wall. The repair removed failed material and reconstructed the slope at 1.5H:1V using engineered fill. Nine-foot percussion-driven anchors at three-foot spacing restrained shallow soil movement, while a vegetated TRM confined surface soils and controlled erosion. Crest and toe anchor trenches, twist pins, and secured overlaps held the mat in place. Stability analysis showed a minimum calculated factor of safety of 1.51, exceeding the 1.50 design requirement; anchor pullout resistance was also considered.<br /><br />Construction avoided disturbance to the roadway and stream, and the modular design allows expansion if further stabilization is needed. Eight months after installation, vegetation had reestablished, with no visible erosion or renewed movement.<br /><br />The project demonstrates that an anchored TRM can provide an economical, relatively rapid solution when the failure mechanism is clearly shallow. Its effectiveness depends on appropriate drainage and successful vegetation establishment. The system is not a substitute for measures designed to stabilize deep or global failures.

Keywords

Hurricane Helene

roadway embankment

slope stabilization

shallow failure

anchored TRM

turf reinforcement mat

engineered fill

erosion control

soil anchors

vegetated repair